chore: add dependabot cooldown

One of the things I need to worry about with Anubis is the idea that
could pwn a dependency and then get malicious code into prod without
realizing it, a-la Jia Tan. Given that Anubis relies on tools like
Dependabot to manage updating dependencies (good for other reasons),
it makes sense to have Dependabot have a 7 day cooldown for new
versions of dependencies.

This follows the advice from Yossarian on their blog at [1]. Thanks
for the post and easy to copy/paste snippets!

[1]: https://blog.yossarian.net/2025/11/21/We-should-all-be-using-dependency-cooldowns

Signed-off-by: Xe Iaso <me@xeiaso.net>

Author: Xe

.github/dependabot.yml

@@ -8,6 +8,8 @@ updates:
       github-actions:
         patterns:
           - "*"
+    cooldown:
+      default-days: 7
 
   - package-ecosystem: gomod
     directory: /
@@ -17,6 +19,8 @@ updates:
       gomod:
         patterns:
           - "*"
+    cooldown:
+      default-days: 7
 
   - package-ecosystem: npm
     directory: /
@@ -26,3 +30,5 @@ updates:
       npm:
         patterns:
           - "*"
+    cooldown:
+      default-days: 7